We develop a theory of team adaptation that centers on team knowledge structures and coordination processes. Specifically, we explain that when a team’s task changes, there may be a disruption in the extent to which their team mental model (TMM) fits the current situation. Whether this is the case is likely to depend on team compositional factors, emergent states, and structural characteristics of the team. When there is a lack of correspondence between the TMM and the situation, this then requires a shift in the extent to which the team uses implicit or explicit coordination processes. We also explain that the team performance phase matters, such that during action phases, a prevalence of implicit coordination relative to explicit coordination results in greater effectiveness; during a transition phase, the opposite is likely. In this way, we address central questions in the field: what types of task changes require team adaptive response, what happens during the adaptation process, and how this influences team effectiveness over time.